Heretofore, in meter apparatuses for vehicles such as automobiles and railroad cars, various kinds of alert buzzers are mounted on their circuit boards. For example, alert buzzers are designed to generate sounds during rear drive operation of a vehicle so as to draw driver's attention to a rear side and the like of the vehicle, or to generate sounds when a door is closed while a key is being at an off position so as to prevent a key from being trapped inside a car compartment.
In some vehicles to be used in places where a car speed is restricted, alert buzzers are rung if the vehicles are beyond a given vehicle speed.
Various kinds of sound-generating elements are provided on circuit boards, besides the buzzers aiming at drawing attentions. Such sound-generating elements generate sounds according to their objects under given conditions.
However, the sound-generating elements generate sounds at predetermined sound volume and tone (hereinafter, being hereinafter collectively called “sound pressure level”) only.
It is desired that the sound pressure levels are adjusted depending upon the kinds and the grades of the vehicles or the narrow or wide spaces of vehicle compartments.
In case that the sound pressure level of a sound-generating element is to be adjusted, the sound-generating element must be replaced by another giving a different sound pressure level. In some cases, not only a sound-generating element is exchanged, but also a driving circuit for the sound-generating element needs to be replaced by one fitting to the replaced sound-generating element. See JP-A 8-207660.
However, it is not easy to exchange the sound-generating element once mounted on the circuit board so as to change the sound pressure level. There was a fear that the circuit board might be damaged during exchanging work or other metering elements provided on the circuit boards might be broken.
Further, some sound-generating elements cannot be detachably attached to the circuit boards. In such cases, there is no way to change the sound pressure level.